Known detonators usually comprise a housing containing an explosive charge with a pair of fusehead conductors; passage of a current through these conductors causes the detonator to explode. Whilst this construction of detonator has the advantage of simplicity, it has very serious disadvantages from the point of view of safety and also from the point of view of ease of unauthorised use.
The main problem from the point of view of safety is that the detonators are susceptible to inadvertent operation because the fusehead conductors can pick up stray electromagnetic radiation or induced currents due to magnetic or electric fields. Handling of known detonators can therefore be somewhat hazardous.
From the point of view of security, known detonators suffer from the disadvantage that they can be actuated by any electrical device which supplies sufficient electrical current to the fusehead conductors. Thus, the detonators can be used for illegal purposes if they fall into the wrong hands.